【创新设计】2016-2017学年高中英语 Unit 2 Healthy eating Period Three Grammar Writing课时作业 新人教版必修3.doc

Period Three　Grammar Writing Part One　Grammar 用适当的情态动词填空 1．In some parts of the world，you must/have to boil the water before drinking it. 2．I didn’t see her in the meeting room this morning.She must have missed the meeting. 3．He can’t/couldn’t have stayed at home this morning.I saw him shopping in another town. 4．I can’t find Mr.Smith anywhere in the office building.Where can/could/might he have gone? 5．You ought to keep a simple first aid box at home for any accidents. 6．If she is completely well，she ought to be back at school today. 7．You needn’t run，for we have enough time to catch the train. 8．—You should have finished the article.The deadline is last Friday. —Sorry.I have been busy these days.Could you give me 3 more days? 9．Michael can’t be a policeman for he’s much too short. 10．He must have caught a bad cold last night，for his forehead felt burning. 情态动词(Ⅱ) 1．ought to与ought not to (1)ought to意为“应该，应当”，其后必须跟动词原形，只有一种形式，没有人称和数的变化。 You ought to make an apology to Joan. (2)ought to表示推测。 Jeffrey ought to be there by now. (3)ought to的否定形式为ought not to或oughtn’t to，其一般疑问句形式是将ought置于主语前。 You ought not to/oughtn’t to be late for such an important meeting. Ought I to hand in my composition now? (4)“ought to＋have done”结构相当于“should＋have done”结构，表示“本应该做某事而事实上并没有做”，其否定结构表示“不该做某事实际上却做了”。 You are late.You ought to/should have arrived five minutes earlier. We oughtn’t to/shouldn’t have told him the news. 2．have to，don’t have to与mustn’t (1)情态动词have to(口语中说成have got to)表示客观需要做的事情，意为“必须；不得不”。有时态、人称和数的变化，其否定式和疑问式应由助动词do构成。 I have to be off now.My mum is expecting me. The little boy has to do lots of housework，for his parents have been suffering from illness. It rained heavily，so the children had to stay at home. (2)have to的否定式为don’t have to，表示“没有义务或必要做某事”，意为“不必”，常可以回答must提问的一般疑问句。而must的否定式mustn’t表示“禁止”。 You don’t have to come here tomorrow. —Must I do it at once? —No，you needn’t(＝No，you don’t have to)． All these exhibits mustn’t be touched. (3)have to和must的区别。它们虽然意思相近，但仍有区别：